The present invention relates to a ground and rock anchor, comprising a longitudinally stable, flexible tensile member, an anchorage part, in which the tensile member is fixed by the one end region, and an anchor head device, in which the tensile member is held by the other end region, which anchorage part is designed to be introduced into a drilled hole in the ground or rock and anchored therein.
Such ground and rock anchors serve in particular to stabilise slopes and rock faces, by introducing the forces to be absorbed by the anchorage part in the surface region of the ground and rock masses to be stabilised into deeper-lying stable soil layers. To transfer these forces from the anchorage part into the deeper-lying soil layers, a tensile member is used which is conventionally formed from a bar or wire strands, which are anchored in the deeper soil layers. To this end, these bars or wire strands are fixed by way of a mortar composition injected into the corresponding drilled hole. The anchor head device allows the tensile member to be tensioned, while an anchorage plate, on which a supporting section is supported, allows the surface soil or the rock masses to be appropriately stabilised.
Such ground and rock anchors are intended for permanent use, which means that the corresponding components of the ground and rock anchors must in particular be protected against corrosion. To this end, the most varied methods are known; for example the tensile member may be inserted into a plastics sheath, or the tensile members may also be accommodated in plastics pipes, which are filled with grease, for example.
Production of such corrosion-protected ground and rock anchors is relatively complex; in particular it is also necessary for such ground and rock anchors to be tested in the installed state, to establish whether corrosion has set in, which can have a very negative effect on the strength of such ground and rock anchors. Such monitoring processes are performed for example in known manner by resistance measurements, which is likewise complex.
It is desirable to provide a ground and rock anchor which is simple to produce, and with which in particular anchorage in the drilled hole and also at the anchorage part may take place optimally.
According to an aspect of the invention, the longitudinally stable, flexible tensile member comprises at least one first loop at least at the one end region which is fixed in the anchorage part, and that the anchorage part is a substantially prismatic or cylindrical longitudinal body, which is formed of a hardenable composition, by which the at least one first loop of the longitudinally stable, flexible tensile member is surrounded.
The anchorage part with the at least one first loop of the longitudinally stable, flexible tensile member fixed therein is prefabricated, and it is therefore ensured that fixing of this loop in the anchorage part is optimal. This longitudinal body formed from a hardenable composition and having the fixed tensile member is inserted into the drilled hole and, by injecting a further hardenable composition into the drilled hole, the longitudinal body is anchored and held optimally at the bottom of the drilled hole.
The longitudinally stable, flexible tensile member is advantageously made from a fibre reinforced plastics material, preferably carbon fibre reinforced plastics material, whereby corrosion can be ruled out. Such a tensile member additionally has the advantage of being pliable; the flexible tensile member may for example be rolled up for transport of the ground and rock anchor, which saves space with regard to the lengthwise extent of such rock anchors. Through the possibility of rolling up or bending over the longitudinally stable, flexible tensile member the space requirement means that only a minimal amount of space is required in front of the drilled hole on insertion of the ground and rock anchor.
Advantageously, the longitudinally stable, flexible tensile member consists of a plurality of layers, wherein in the one end region, which is fixed in the anchorage part, each layer or a bundle of layers in each case forms a separate first loop, which separate first loops each have different lengths. This results in progressive fixing of this tensile member in the anchorage part, whereby anchorage and force absorption is unproved significantly.
A further advantageous configuration of an aspect of the invention consists in the fact that the hardenable composition from which the anchorage part is made a mortar-type composition. This mortar-type composition can be cast into a mould in which the one end region of the flexible tensile member has been inserted, whereby a fixed bond is ensured between the mortar-type composition after hardening thereof and the first loops of the flexible tensile member.
Advantageously the surface of the anchorage part is provided with structures which may be provided in the mould in which the anchorage part is produced and in which the first loops are cast, whereby an optimal bond arises between the surface of the anchorage part and the hardenable composition injected into the drilled hole.
Advantageously, the structures consist of ribs projecting above the surface of the anchorage part, which ribs are oriented substantially transversely to the direction of pull of the force acting on the tensile member and on the anchorage part, which results in optimal fixing.
A further advantageous configuration of an aspect of the invention consists in the fact that the anchorage part is surrounded by tension rings at least over sub-regions of its length. These tension rings prevent the longitudinal body hardened from a mortar-type composition from breaking away in these regions.
Advantageously a tension ring is arranged in the entry region of the tensile member into the anchorage part, since force absorption is very great in this region.
Advantageously these tension rings are each arranged in the region of the ends of the first loops of the tensile member in the anchorage part, since in these regions the risk of breaking away is at its greatest.
A further advantageous configuration of an aspect of the invention consists in forming the other end region of the tensile member as a second loop. The tensile member may thus be produced as an endless loop, which has a positive effect on the strength thereof.
Advantageously, a bolt is provided which is arranged in the anchor head device transversely to the direction of pull and over which the second loop of the tensile member can be simply laid, the tensile member being held optimally in the anchor head device.
The bolt is mounted in a tensioning device, which is arranged in the anchor head device, whereby the tensile member may be simply tensioned to a greater or lesser extent by displacing the bolt.